Discussion 59 



higher than we have found in the child with hypernatraemia. The urine 

 of the infant with hypernatraemia is also low in sodium. One finds both 

 the gut and kidney strongly retaining sodium beyond what might seem 

 an optimal degree. I wonder what this means? 



Young: This hanging on to sodium without any excess excretion in the 

 urine is just what happens in experimental dehydration. If you are not 

 putting sodium into the body either by mouth or intravenously, there is 

 never a high output of sodium in the urine, even if the serum sodium is 

 rising. There is nothing extraordinary about that in the baby. Why the 

 kidneys function that way, I do not know, but they did so under condi- 

 tions of experimental dehydration in the normal adults studied by Dr. 

 Black, Prof. McCance, and myself (1944. J. Physiol. 102, 406). 



Desaulles : Is there any possibility of making chromatograms of blood 

 and urine steroids in the kind of case you have just described, Prof. 

 Wallace? The aldosterone content was very high, wasn't it? 



Wallace : We can obtain such chromatograms but I am always told that 

 close to a litre of blood or urine is required, and these are tiny children. 



Desaulles: For aldosterone determination 100 ml. is enough. The con- 

 dition fits so well with the picture of a very high aldosterone output that 

 I wonder if those cases cannot be explained by the very high aldosterone 

 levels. In these all the sodium is retained without changes in the water 

 content. In the recovery period you have water retention and a decrease 

 in aldosterone. After that you reach a steady state, i.e. a new form 

 of equilibrium, though it is perhaps not the true equilibrium. That is 

 only a hypothesis for the moment, until we have more precise values. 



Davson : Does aldosterone influence the absorption of water by the 

 intestine? 



Desaulles: I have no precise data. 



Black : I want to express agreement with Dr. Fourman, because I think 

 that none of the alleged clinical tests for water depletion, such as the 

 'fingerprint' test, are any good. There is also another possible cause of 

 so-called cerebral salt-wasting. We had a patient in with hemiplegia and 

 a period of hypotension. Ten days later he was mopping up about six 

 litres of saline fluid a day and losing it through his urine. The only sug- 

 gestion I can make is that during the period of hypotension he sustained 

 tubular damage and that later he was in a renal salt-losing state, in 

 which the cerebral part was just an accident. I have seen this before and 

 I think it is particularly liable to happen in older people who have a 

 smaller renal reserve. 



Fourman : I think that is a very interesting comment. The very severe 

 dehydrations probably do produce renal lesions and we have been 

 wondering whether that accounts for the systemic acidosis, which is so 

 often a prominent feature. 



Wallace: Chloride acidosis always occurs. 



Fourman: What is the plasma bicarbonate? 



Wallace: In our experience it is always low. Chloride is making bicar- 

 bonate forfeit its place in serum. 



Desaulles : Dr. Fourman, was it possible to make steroid determinations 

 in your case? 



